This invention pertains to continuous passive motion methods and means, and in particular, to such continuous passive motion methods and means as they are applied in the treatment and/or prevention of back pain and the providing of back comfort,
Back pain is a very widespread malady in the United States. Lower back pain can be caused by disease, injury or congenital defect. There are many different types of relevant therapeutic machines on the market today. There have been a number of patents issued in the continuous passive motion field including the U.S. Pat. No. 4,981,131, issued to the applicant Rowland G. Hazard for a Passive Motion Back Support. This patent shows a pneumatic based apparatus for providing continuous passive motion in treating or preventing back pain. A number of devices provide mechanical apparatus for the same purpose. The key difficulty inherent in these designs and requiring solution in order to optimize the user's comfort is the need for integrated automatic force feedback to control the support devices. Without such feedback, devices cannot accommodate variations in the user's spinal compliance, posture and position while providing the desired spinal mobilization comfortably and safely. What is needed is a method and means that will provide force feedback for mechanical and pneumatic devices that deliver back support and/or continuous passive spinal motion. A type of device related to providing massage is shown by the U.S. Pat. No. 5,083,552 issued to Lipowitz for a device that provides vertical compression for the user very rapidly giving a massage effect. The high and low pressure limits of Lipowitz are continuously cycling in the very fast cycle time of half a second to two seconds in order to provide massage. As opposed to the type of control, which is only adequate for massage, safe and comfortable spinal mobilization through a continuous passive motion support requires a pressure feedback system with operating characteristics which vary between phases of the motion cycles. What is also needed is a device and a method which builds up to a preset force range and then holds the force constant for a minimum of five seconds or more during which time movement may or may not occur.
It is the object of this invention to teach a method of and means for providing force feedback in continuous passive motion systems which avoids the disadvantages and limitations, recited above. Another object of this invention is to provide force feedback for producing spinal motion using a prolongation of certain phases of cycle time in order to have the user remain comfortable and safe.